It is known that unsaturated carboxylic acids may be reduced to an ester or to the corresponding alcohol. However, the reducing catalysts which have heretofore been employed are not selective in the hydrogenation process, and thus the reductive process usually results in eliminating the retention of the unsaturation in the carbon chain. The compound which is obtained is therefore a saturated ester or alcohol. This is true when utilizing catalysts such as a mixture of copper and chromium oxide or rhenium catalysts which may be used in either a supported or unsupported state or which may also contain a noble metal of Group VIII of the Periodic Table, such as platinum, palladium or ruthenium.
In many instances, it is desirable to retain the unsaturation of the carbon chain when obtaining either alcohols or esters of the starting unsaturated carboxylic acid. As will hereinafter be shown in greater detail, it has now been discovered that a process for effecting the reduction of unsaturated carboxylic acids may be effected by utilizing certain catalytic compositions of matter and also by utilizing certain modifications of the process to obtain esters or alcohols of unsaturated carboxylic acids in which the double bonds present in the original acid are retained in the reaction product to a greater extent than without the catalyst and process modifications.